Semiconductor device and manufacturing method thereof

ABSTRACT

A semiconductor device includes first and second FETs including first and second channel regions, respectively. The first and second FETs include first and second gate structures, respectively. The first and second gate structures include first and second gate dielectric layers formed over the first and second channel regions and first and second gate electrode layers formed over the first and second gate dielectric layers. The first and second gate structures are aligned along a first direction. The first gate structure and the second gate structure are separated by a separation plug made of an insulating material. A width of the separation plug in a second direction perpendicular to the first direction is smaller than a width of the first gate structure in the second direction, when viewed in plan view.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. Ser. No.14/932,383, filed Nov. 4, 2015, the subject matter of which isincorporated herein by reference in entirety.

TECHNICAL FIELD

The disclosure relates to a semiconductor integrated circuit, and moreparticularly to a semiconductor device having a fin structure and itsmanufacturing process.

BACKGROUND

As the semiconductor industry has progressed into nanometer technologyprocess nodes in pursuit of higher device density, higher performance,and lower costs, challenges from both fabrication and design issues haveresulted in the development of three-dimensional designs, such as a finfield effect transistor (Fin FET). Fin FET devices typically includesemiconductor fins with high aspect ratios and in which channel andsource/drain regions of semiconductor transistor devices are formed. Agate is formed over and along the sides of the fin structures (e.g.,wrapping) utilizing the advantage of the increased surface area of thechannel and source/drain regions to produce faster, more reliable andbetter-controlled semiconductor transistor devices. A metal gatestructure together with a high-k gate dielectric having a high electricdielectric constant is often used in Fin FET device, and is fabricatedby a gate-replacement technology.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIGS. 1-10D show exemplary sequential processes for manufacturing an FETdevice according to one embodiment of the present disclosure.

FIGS. 11A and 11B show an exemplary structure of an FET device accordingto another embodiment of the present disclosure.

FIG. 12 shows an exemplary structure of an FET device according to oneembodiment of the present disclosure.

FIG. 13 shows an exemplary structure of an FET device according toanother embodiment of the present disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the invention. Specific embodiments or examples of components andarrangements are described below to simplify the present disclosure.These are, of course, merely examples and are not intended to belimiting. For example, dimensions of elements are not limited to thedisclosed range or values, but may depend upon process conditions and/ordesired properties of the device. Moreover, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed interposing the first and second features, suchthat the first and second features may not be in direct contact. Variousfeatures may be arbitrarily drawn in different scales for simplicity andclarity.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“made of” may mean either “comprising” or “consisting of.”

FIGS. 1-10D show cross sectional and/or plan views of exemplarysequential processes of manufacturing the Fin FET device according toone embodiment of the present disclosure. It is understood thatadditional operations can be provided before, during, and afterprocesses shown by FIGS. 1-10D, and some of the operations describedbelow can be replaced or eliminated, for additional embodiments of themethod. The order of the operations/processes may be interchangeable.

FIG. 1 shows an exemplary cross sectional view in which fin structures20 are formed over a substrate 10. To fabricate a fin structure, a masklayer is formed over the substrate (e.g., a semiconductor wafer) by, forexample, a thermal oxidation process and/or a chemical vapor deposition(CVD) process. The substrate is, for example, a p-type silicon substratewith an impurity concentration being in a range from about 1×10¹⁵ cm⁻³and about 5×10¹⁵ cm⁻³. In other embodiments, The substrate is an n-typesilicon substrate with an impurity concentration being in a range fromabout 1×10¹⁵ cm⁻³ and about 5×10¹⁵ cm⁻³.

Alternatively, the substrate 10 may comprise another elementarysemiconductor, such as germanium; a compound semiconductor includingIV-IV compound semiconductors such as SiC and SiGe, III-V compoundsemiconductors such as GaAs, GaP, GaN, InP, InAs, InSb, GaAsP, AlGaN,AlInAs, AlGaAs, GaInAs, GaInP, and/or GaInAsP; or combinations thereof.In one embodiment, the substrate 10 is a silicon layer of an SOI(silicon-on insulator) substrate. When an SOI substrate is used, the finstructure may protrude from the silicon layer of the SOI substrate ormay protrude from the insulator layer of the SOI substrate. In thelatter case, the silicon layer of the SOI substrate is used to form thefin structure. Amorphous substrates, such as amorphous Si or amorphousSiC, or insulating material, such as silicon oxide may also be used asthe substrate 10. The substrate 10 may include various regions that havebeen suitably doped with impurities (e.g., p-type or n-typeconductivity).

The mask layer includes, for example, a pad oxide (e.g., silicon oxide)layer and a silicon nitride mask layer in some embodiments. The padoxide layer may be formed by using thermal oxidation or a CVD process.The silicon nitride mask layer may be formed by a physical vapordeposition (PVD), such as sputtering method, a CVD, plasma-enhancedchemical vapor deposition (PECVD), an atmospheric pressure chemicalvapor deposition (APCVD), a low-pressure CVD (LPCVD), a high densityplasma CVD (HDPCVD), an atomic layer deposition (ALD), and/or otherprocesses.

The thickness of the pad oxide layer is in a range from about 2 nm toabout 15 nm and the thickness of the silicon nitride mask layer is in arange from about 2 nm to about 50 nm in some embodiments. A mask patternis further formed over the mask layer. The mask pattern is, for example,a photo resist pattern formed by photo lithography.

By using the mask pattern as an etching mask, a hard mask pattern 100 ofthe pad oxide layer 106 and the silicon nitride mask layer 107 isformed.

By using the hard mask pattern as an etching mask, the substrate ispatterned into fin structures 20 by trench etching using a dry etchingmethod and/or a wet etching method.

The fin structures 20 disposed over the substrate 10 are made of thesame material as the substrate 10 and continuously extend from thesubstrate 10 in one embodiment. The fin structures 20 may be intrinsic,or appropriately doped with an n-type impurity or a p-type impurity.

In FIG. 1, four fin structures 20 are disposed. These fin structures areused for a p-type Fin FET and/or an n-type Fin FET. The number of thefin structures is not limited to four. The numbers may be as small asone, or more than four. In addition, one of more dummy fin structuresmay be disposed adjacent both sides of the fin structures 20 to improvepattern fidelity in patterning processes. The width W1 of the finstructures 20 is in a range from about 5 nm to about 40 nm in someembodiments, and is in a range from about 7 nm to about 20 nm in certainembodiments. The height H1 of the fin structures 20 is in a range fromabout 100 nm to about 300 nm in some embodiments, and is a range ofabout 50 nm to 100 nm in other embodiments. When the heights of the finstructures are not uniform, the height from the substrate may bemeasured from the plane that corresponds to the average heights of thefin structures.

As shown in FIG. 2, an insulating material layer 50 to form an isolationinsulating layer is formed over the substrate 10 so as to fully coverthe fin structures 20.

The insulating material for the isolation insulating layer 50 is madeof, for example, silicon dioxide formed by LPCVD (low pressure chemicalvapor deposition), plasma-CVD or flowable CVD. In the flowable CVD,flowable dielectric materials instead of silicon oxide are deposited.Flowable dielectric materials, as their name suggest, can “flow” duringdeposition to fill gaps or spaces with a high aspect ratio. Usually,various chemistries are added to silicon-containing precursors to allowthe deposited film to flow. In some embodiments, nitrogen hydride bondsare added. Examples of flowable dielectric precursors, particularlyflowable silicon oxide precursors, include a silicate, a siloxane, amethyl silsesquioxane (MSQ), a hydrogen silsesquioxane (HSQ), an MSQ/HSQa perhydrosilazane (TCPS), a perhydro-polysilazane (PSZ), a tetraethylorthosilicate (TEOS), or a silyl-amine, such as trisilylamine (TSA).These flowable silicon oxide materials are formed in amultiple-operation process. After the flowable film is deposited, it iscured and then annealed to remove un-desired element(s) to form siliconoxide. When the un-desired element(s) is removed, the flowable filmdensifies and shrinks. In some embodiments, multiple anneal processesare conducted. The flowable film is cured and annealed more than once.The isolation insulating layer 50 may be SOG, SiO, SiON, SiOCN orfluorine-doped silicate glass (FSG). The isolation insulating layer 50may be doped with boron and/or phosphorous.

After forming the isolation insulating layer 50, a planarizationoperation is performed so as to remove upper part of the isolationinsulating layer 50 and the mask layer 100 including the pad oxide layer106 and the silicon nitride mask layer 107. Then, the isolationinsulating layer 50 is further removed so that an upper part of the finstructures 20, which is to become a channel region, is exposed, as shownin FIG. 3.

After forming the isolation insulating layer 50, a thermal process, forexample, an anneal process, is optionally performed to improve thequality of the isolation insulating layer 50. In certain embodiments,the thermal process is performed by using rapid thermal annealing (RTA)at a temperature in a range from about 900° C. to about 1050° C. forabout 1.5 seconds to about 10 seconds in inert gas ambient, for example,N₂, Ar or He ambient.

After the upper portions of the fin structures 20 are exposed from theisolation insulating layer 50, a gate insulating layer 105 and a polysilicon layer are formed over the isolation insulating layer 50 and theexposed fin structures 20, and then patterning operations are performedso as to obtain a gate layer 110 made of poly silicon, as shown in FIGS.4A-4D. The gate insulating layer 105 may be silicon oxide formed by CVD,PVD, ALD, e-beam evaporation, or other suitable process. A thickness ofthe poly silicon layer is in a range from about 5 to about 100 nm insome embodiments. In the gate replacement technology described withFIGS. 9A-10D, the gate insulating layer 105 and gate layer 100 are bothdummy layers which are eventually removed.

After the patterning the poly silicon layer, sidewall insulating layers80 (sidewall spacers) are also formed at both side faces of the gatelayer 110. The sidewall insulating layers 80 is made of one or morelayers of silicon oxide or silicon nitride based materials such as SiN,SiCN, SiON or SiOCN. In one embodiment, silicon nitride is used.

After the sidewall insulating layers 80 are formed, an insulating layer90 to be used as a contact-etch stop layer (CESL) is formed over thepoly silicon layer 110 and the sidewall insulating layer 80. The CESLlayer 90 is made of one or more layers of silicon oxide or siliconnitride based materials such as SiN, SiCN, SiON or SiOCN. In oneembodiment, silicon nitride is used.

Further, an interlayer dielectric layer (ILD) 70 is formed in spacesbetween the gate layers 110 with the side-wall insulating layers 80 andthe CESL 90 and over the gate layer 110. The ILD 70 may include siliconoxide, silicon nitride, silicon oxynitride (SiON), SiOCN, fluorine-dopedsilicate glass (FSG), or a low-K dielectric material, and may be made ofCVD or other suitable process. The insulating material for the isolationinsulating layer 50 may be the same as or different from that for theILD 70.

Planarization operations, such as an etch-back process and/or a chemicalmechanical polishing (CMP) process, are performed, so as to obtain thestructure shown in FIGS. 4A-4D. FIG. 4A is a plane view (top view) andFIG. 4B is a perspective view of the Fin FET device after the gate layer110 and the interlayer dielectric layer 70 are formed. FIGS. 1-3 and 4Ccorrespond to cross sectional views along line X1-X1 in FIG. 4A, FIG. 4Dcorrespond to a cross sectional view along line Y1-Y1 in FIG. 4A, andFIG. 4B corresponds to the enclosed portion B1 in FIG. 4A.

As shown in FIGS. 4A and 4B, the gate layers 110 are formed in aline-and-space arrangement extending in one direction (X direction) witha constant pitch. The gate layers 110 may include another line-and-spacearrangement extending in another direction (Y direction) perpendicularto the one direction, and another line-and-space arrangement withdifferent dimensions.

The gate layers 110 cover the channel regions of the Fin FETs formedwith the fin structures 20. In other words, the gate layers 110 areformed over the channel regions. The fin structures not covered by thegate layers will become source/drain regions by appropriate source/drainfabrication operations.

Next, as shown in FIGS. 5A-5C, a mask pattern 120 is formed over thestructure shown in FIGS. 4A-4D. FIG. 5A is a cross sectional viewcorresponding to line X1-X1 in FIG. 4A, FIG. 5B is a cross sectionalview corresponding to line Y1-Y1 in FIG. 4A, and FIG. 5C is a top view.The mask pattern 120 is formed by, for example, a material having a highetching selectivity to poly silicon. In one embodiment, the mask pattern120 is made of silicon nitride. The mask pattern 120 has an opening 125.A width of the opening 125 along the X direction is in a range fromabout 5 nm to about 100 nm in some embodiments, and in a range fromabout 10 nm to 30 nm in other embodiments. The width W2 of the opening125 along the Y direction is adjusted to expose a desired number of gatestructures. In FIG. 5C, the width of the opening 125 along the Ydirection is such a length that two gate structures are exposed in theopening 125, and the edges of the opening in the Y direction are locatedbetween the adjacent gate structures over the ILD 70.

As shown in FIGS. 6A and 6B, by using the mask pattern 120 as an etchingmask, a part of gate layer 110 and the gate insulating layer 105 areremoved, so as to obtain a separation opening 130 that separates thegate layers 110. The etching of the gate layer is performed by plasmaetching using gases including CH₄, CF₄, CH₂F₂, CHF₃, O₂, HBr, Cl₂, NF₃,N₂ and/or He under a pressure of 3 to 20 mTorr, in some embodiments.

The etching of the gate layer 110 accompanies etching the oxide layers(with different etching conditions than the poly silicon etching)including the gate insulating layer 105. During the oxide etching, theupper portion 71 of the ILD 70 and the surface portion 51 of theisolation insulating layer 50 are also etched, as shown in FIGS. 6A and6B. The depth D1, which is an etched depth of the surface portion 51 ofthe isolation insulating layer 50 is in a range from about 1 nm to about10 nm.

It is noted that the cross sectional views of the opening 130 has arectangular shape in FIG. 6A, but in some embodiments, the opening 130has a tapered shape having a larger top size and a smaller bottom size.Further, as shown in FIG. 6B, the sidewall insulating layers 80 and theCESL 90 remain in the openings 130.

Then, as shown in FIGS. 7A and 7B, a thin filling insulating layer 140and a thick filling insulating layer 150 are formed over the resultantstructure of FIGS. 6A and 6B.

The thin insulating layer 140 is made of, for example, the same materialas the gate insulating layer 105. In this embodiment, silicon oxide isused. The thin filling insulating layer 140 is made by CVD or ALD. Thethickness of the thin filling insulating layer 140 is in a range fromabout 3 nm to about 25 nm in some embodiments, and is in a range fromabout 5 nm to about 15 nm in other embodiments. As shown in FIGS. 7A and7B, the thin filling insulating layer 140 is conformally formed in theopening 130 and over the mask pattern 120.

The thick filling insulating layer 150 is made of silicon oxide orsilicon nitride based materials such as SiN, SiCN, SiON or SiOCN. In oneembodiment, silicon nitride is used. The thick filling insulating layer150 is conformally formed over the thin filling insulating layer 140 inthe opening 130 and over the mask pattern 120.

After the opening 130 is filled by the thin filling insulating layer 140and the thick filling insulating layer 150, a planarization operationsuch as a CMP process is performed to expose the upper surface of thegate layers 110, as shown in FIGS. 8A and 8B. In other words, the gatelayers 110 function as a stopper for the CMP process. By thisplanarization operation, a separation plug 155 is formed.

After the planarization operation to expose the gate layers 110, thegate layers 110 and gate insulating layer 105 (i.e., dummy layers) areremoved by using dry etching and/or wet etching, thereby forming gateopenings 145, as shown in FIGS. 9A and 9B. During the removal of thegate insulating layer 105, since the thin filling insulating layer 140is made of the same material as the gate insulating layer 105 (e.g.,silicon oxide), part of the thin filling insulating layer 140 exposed tothe etching process is also removed. As shown in FIG. 9A, the thinfilling insulating layer 140 which has been disposed between the gatelayer 110 and the thick filling insulating layer 150 is removed.

Next, as shown in FIG. 10A-10D, metal gate structures including a gatedielectric layer 160 and a metal gate electrode layer 170 are formed.

In certain embodiments, the gate dielectric layer 160 includes one ormore layers of dielectric material, such as silicon oxide, siliconnitride, or high-k dielectric material, other suitable dielectricmaterial, and/or combinations thereof. Examples of high-k dielectricmaterial include HfO₂, HfSiO, HfSiON, HfTaO, HfSiO, HfZrO, zirconiumoxide, aluminum oxide, titanium oxide, hafnium dioxide-alumina(HfO₂—Al₂O₃) alloy, other suitable high-k dielectric materials, and/orcombinations thereof.

The metal gate electrode layer 170 includes any suitable material, suchas aluminum, copper, titanium, tantalum, tungsten, cobalt, molybdenum,tantalum nitride, nickel silicide, cobalt silicide, TiN, WN, TiAl,TiAlN, TaCN, TaC, TaSiN, metal alloys, other suitable materials, and/orcombinations thereof.

In certain embodiments, one or more work function adjustment layers (notshown) are also disposed between the gate dielectric layer 160 and themetal gate electrode layer 170. The work function adjustment layers aremade of a conductive material such as a single layer of TiN, TaN, TaAlC,TiC, TaC, Co, Al, TiAl, HfTi, TiSi, TaSi or TiAlC, or a multilayer oftwo or more of these materials. For the n-channel FET, one or more ofTaN, TaAlC, TiN, TiC, Co, TiAl, HfTi, TiSi and TaSi is used as the workfunction adjustment layer, and for the p-channel FET, one or more ofTiAlC, Al, TiAl, TaN, TaAlC, TiN, TiC and Co is used as the workfunction adjustment layer. The work function adjustment layer may beformed by ALD, PVD, CVD, e-beam evaporation, or other suitable process.Further, the work function adjustment layer may be formed separately forthe n-channel Fin FET and the p-channel Fin FET which may use differentmetal layers.

In forming the metal gate structures, the gate dielectric layer, thework function adjustment layer and the gate electrode layer are formedby suitable film forming method, for example, CVD or ALD for gatedielectric layer, and CVD, PVD, ALD or electroplating for the metallayers, and then a planarization operation such as CMP is performed.

FIGS. 10C and 10D show top views after the metal gate structures areformed. FIG. 10D is an enlarged view of the enclosed portion B2 in FIG.10C. As shown in FIGS. 10C and 10D, the metal gate structures (160, 170)are separated by a separation plug 155. As shown in FIG. 10D, the widthW3 along the Y direction (perpendicular to the X direction which is anextending direction of the metal gate structures) of the separation plugis smaller than the width W4 along the Y direction of the gate structureincluding the gate dielectric layer 160 and the gate electrode layer 170due to the thin insulating filling layer 140. In some embodiments, thewidth W3 along the Y direction of the separation plug is smaller thanthe width W5 along the Y direction of the gate dielectric layer 160.

It is understood that the structure shown in FIGS. 10A-10D undergoesfurther CMOS processes to form various features such as interconnectvias, interconnect metal layers, passivation layers, etc.

In the foregoing embodiment, the gate layer 110 is separated into twogate layers. However, in other embodiments, the gate layer 110 isseparated into more than two gate layers by the patterning operations ofFIGS. 6A-8B. In such a case, as shown in FIG. 11A, multiple gatestructures each including the gate electrode layer 170 are aligned andseparated by separation plugs 155.

Further, the gate layer 110 has two ends in its longitudinal directionbefore the separation operation. In some embodiments, the separationplug 155 is formed in at least one of these ends, as shown in area B3 ofFIG. 11A. In such a case, the gate structure including the gateelectrode layer 170 is sandwiched by two separation plugs 155. In someembodiment, both ends have the separation plugs 155.

In other embodiments, the separation plug 155 is not formed in at leastone of the ends, as shown in area B4 of FIG. 11A. In such a case, oneend of the gate structure including the gate electrode layer 170 has aseparation plug 155 and the other end of the gate structure has thestructure shown in FIG. 11B. FIG. 11B is a cross sectional view of lineB5 of FIG. 11A. As shown in FIG. 11B, the gate structure, in particularthe gate dielectric layer 160 is in contact with the ILD 70. In someembodiment, both ends have no separation plugs 155.

In another embodiment, a gate insulating layer 105 is not a dummy layerand is made of dielectric material finally used in the FET device. Insuch a case, a high-k dielectric material described above can be used.When the gate insulating layer 105 is not a dummy layer, the gateinsulating layer 105 is made of a different material than the thinfilling insulating layer 140. In the operation with respect of FIGS. 9Aand 9B, the gate insulating layer 105 (e.g., a high-k dielectricmaterial) is not removed in the openings 145. Then, an additionaloperation to remove the thin filling insulating layer 140 is performedto obtain the structure similar to FIG. 9A, except for the existence ofthe gate insulating layer 105. In this case, the metal gate electrodelayer 170 is in contact with the separation plug 150, as shown in FIG.12, because the formation of the gate dielectric layer 160 (see, FIG.10A) is not necessary.

In the above embodiments, a Fin FET is employed. However, the foregoingtechnologies can be applied to a planar type FET, as shown in FIG. 13.As shown in FIG. 13, the FET includes a channel region 22 of asemiconductor substrate and a gate structure including a gate dielectriclayer 160′ formed over the channel region 22 and a gate electrode layer170′ formed over the gate dielectric layer 160′. The channel regions areseparated by the isolation insulating layers 50 and two gate structuresare separated by a separation plug 155.

The various embodiments or examples described herein offer severaladvantages over the existing art. For example, since the thin insulatingfilling layer 140 is eventually removed, the width in the Y direction ofthe gate space to be filled by metal gate materials can become larger.With the enlarged gate opening, the metal gate materials such as a metalgate electrode material can be fully filled in the opening withoutforming voids.

It will be understood that not all advantages have been necessarilydiscussed herein, no particular advantage is required for allembodiments or examples, and other embodiments or examples may offerdifferent advantages.

In accordance with one aspect of the present disclosure, a semiconductordevice includes a first fin field-effect transistor (Fin FET) and asecond Fin FET. The first Fin FET includes a first fin structureextending in a first direction and a first gate structure. The firstgate structure includes a first gate dielectric layer formed over thefirst fin structure and a first gate electrode layer formed over thefirst gate dielectric layer, and extends in a second directionperpendicular to the first direction. The second Fin FET includes asecond fin structure extending in the first direction and a second gatestructure. The second gate structure includes a second gate dielectriclayer formed over the second fin structure and a second gate electrodeformed over the second gate dielectric layer, and extends in the seconddirection. The first gate structure and the second gate structure arealigned along the second direction. The first gate structure and thesecond gate structure are separated by a separation plug made of aninsulating material. A width of the separation plug in the firstdirection is smaller than a width of the first gate structure in thefirst direction, when viewed in plan view.

In accordance with another aspect of the present disclosure, asemiconductor device includes a first field-effect transistor (FET) anda second FET. The first FET includes a first channel region of asemiconductor substrate and a first gate structure. The first gatestructure includes a first gate dielectric layer formed over the firstchannel region and a first gate electrode layer formed over the firstgate dielectric layer, and extends in a first direction. The second FETincludes a second channel region of the semiconductor substrate and asecond gate structure. The second gate structure includes a second gatedielectric layer formed over the second channel region and a second gateelectrode layer formed over the second gate dielectric layer, andextends in the first direction. The first gate structure and the secondgate structure are aligned along the first direction. The first gatestructure and the second gate structure are separated by a separationplug made of an insulating material. A width of the separation plug in asecond direction perpendicular to the first direction is smaller than awidth of the first gate structure in the second direction, when viewedin plan view.

In accordance with another aspect of the present disclosure, a methodfor manufacturing a semiconductor device includes forming a dummy gatestructure over channel regions formed over a substrate. The dummy gatestructure includes a dummy gate electrode layer, a dummy gate dielectriclayer and sidewall spacer layers disposed on both sides of the dummygate electrode layer. The method includes forming interlayer dielectriclayers at both sides of the dummy gate structure. The method furtherincludes patterning the dummy gate structure so that the dummy gatestructure is divided into at least a first dummy gate structure and asecond dummy gate structure separated by a separation opening. Themethod includes forming a separation plug by filling the separationopening with a first insulating material and a second insulatingmaterial different from the first insulating material. The methodincludes removing the dummy gate electrode layer and the dummy gatedielectric layer from the first dummy gate structure and the seconddummy gate structure, so that a first electrode space and a secondelectrode space are formed and the separation plug is exposed betweenthe first electrode space and the second electrode space. The methodincludes forming a first gate structure and a second gate structure inthe first electrode space and the second electrode space, respectively.During the removing the dummy gate dielectric layer, portions of thefirst insulating material exposed to the first electrode space and thesecond electrode space are removed.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A method for manufacturing a semiconductordevice, comprising: forming a dummy gate structure over a substrate, thedummy gate structure including a dummy gate electrode layer, a dummygate dielectric layer and sidewall spacer layers; forming interlayerdielectric layers at both sides of the dummy gate structure; dividingthe dummy gate structure into at least a first dummy gate structure anda second dummy gate structure, by forming a separation opening; forminga separation plug by filling the separation opening with a firstinsulating material and a second insulating material different from thefirst insulating material; forming a first gate structure and a secondgate structure by replacing the dummy gate electrode layer and the dummygate dielectric layer with a conductive material layer and a dielectriclayer, respectively, wherein, during the replacing the dummy gateelectrode layer and the dummy gate dielectric layer with the conductivematerial layer and the dielectric layer, portions of the firstinsulating material are removed.
 2. The method of claim 1, wherein thedummy gate dielectric layer and the first insulating material are madeof a same material.
 3. The method of claim 1, further comprising forminga third insulating layer over the dummy gate structure before thedividing the dummy gate structure.
 4. The method of claim 3, wherein thedividing the dummy gate structure includes: forming a mask layer overthe dummy gate structure and the interlayer dielectric layer, patterningthe mask layer so as to form an opening pattern; and etching a part ofthe dummy gate structure and the third insulating layer under theopening pattern, thereby forming the separation opening.
 5. The methodof claim 4, wherein during the etching the part of the dummy gatestructure, a part of the interlayer dielectric layer under the openingpattern is etched.
 6. The method of claim 4, wherein the forming aseparation plug includes: forming a blanket layer of the firstinsulating material in the separation opening and over the mask layer;forming a blanket layer of the second insulating material over the firstinsulating material; and removing parts of the second and firstinsulating materials, the mask layer and a part of the interlayerdielectric layer by a planarization operation, so that an upper surfaceof the dummy gate electrode layer is exposed.
 7. The method of claim 4,further comprising: forming fin structures over the substrate; formingan isolation insulating layer over the substrate so that upper portionsof the fin structures are exposed from the isolation insulating layer,wherein channel regions are included in the exposed upper portions ofthe fin structures.
 8. The method of claim 7, wherein in the dividingthe dummy gate, an upper surface of the isolation insulating layer ispartially etched so that a bottom of the separation opening is locatedbelow the upper surface of the isolation insulating layer.
 9. The methodof claim 7, wherein: the replacing the dummy gate electrode layer andthe dummy gate dielectric layer with the conductive material layer andthe dielectric layer includes: removing the dummy gate electrode layerand the dummy gate dielectric layer from the first dummy gate structureand the second dummy gate structure, so that a first electrode space anda second electrode space are formed and the separation plug is exposedbetween the first electrode space and the second electrode space; andforming the dielectric layer and the conductive material in the firstelectrode space and the second electrode space, respectively, after theseparation plug is exposed, the portions of the first insulatingmaterial exposed to the first electrode space and the second electrodespace are removed, and the first insulating material remains between thesecond insulating material and the isolation insulating layer.
 10. Themethod of claim 1, wherein a width of the separation plug in a firstdirection perpendicular to a second direction in which the first andsecond gate structures extend is smaller than a width of the first gatestructure in the first direction, in plan view.
 11. The method of claim1, wherein a layer of the first insulating material is disposed betweenthe separation plug and the sidewall spacer layers, respectively. 12.The method of claim 1, further comprising, before the interlayerdielectric layers are formed, forming a contact-etch stop layer made ofsilicon nitride.
 13. The method of claim 12, wherein in plan view, thefirst and second gate structures and the separation plug are disposedbetween the sidewall spacer layers and layers formed from thecontact-etch stop layer.
 14. The method of claim 1, wherein the firstinsulating material is formed by an atomic layer deposition.
 15. Themethod of claim 1, wherein a thickness of the first insulating materialis in a range from 3 nm to 25 nm.
 16. The method of claim 1, wherein thefirst gate structure includes a first gate electric layer in contactwith the second insulating material of the separation plug.
 17. Themethod of claim 1, wherein the second insulating material is made of asilicon nitride based material and the first insulating material is madeof silicon oxide.
 18. A method for manufacturing a semiconductor device,comprising: forming a dummy gate structure over a substrate, the dummygate structure including a dummy gate electrode layer, a dummy gatedielectric layer and sidewall spacer layers; forming interlayerdielectric layers at both sides of the dummy gate structure; dividingthe dummy gate structure into at least a first dummy gate structure anda second dummy gate structure, by forming a separation opening; forminga separation plug by filling the separation opening with a firstinsulating material and a second insulating material different from thefirst insulating material; forming a first gate structure and a secondgate structure by replacing the dummy gate electrode layer and the dummygate dielectric layer with a conductive material layer and a dielectriclayer, respectively, wherein: during the replacing the dummy gateelectrode layer and the dummy gate dielectric layer with the conductivematerial layer and the dielectric layer, portions of the firstinsulating material are removed, and in plan view, the first and secondgate structures and the separation plug are disposed between sidewallspacer layers and an additional insulating layer.
 19. The method ofclaim 18, wherein: the second insulating material is made of a siliconnitride based material and the first insulating material is made ofsilicon oxide, and the dummy gate dielectric layer is made of siliconoxide.
 20. A method for manufacturing a semiconductor device,comprising: forming a dummy gate structure over a substrate, the dummygate structure including a dummy gate electrode layer, a dummy gatedielectric layer and sidewall spacer layers; forming interlayerdielectric layers at both sides of the dummy gate structure; dividingthe dummy gate structure into at least a first dummy gate structure anda second dummy gate structure, by forming a separation opening; forminga separation plug by filling the separation opening with a firstinsulating material and a second insulating material different from thefirst insulating material; forming a first gate structure and a secondgate structure by replacing the dummy gate electrode layer and the dummygate dielectric layer with a conductive material layer and a dielectriclayer, respectively, wherein: during the replacing the dummy gateelectrode layer and the dummy gate dielectric layer with the conductivematerial layer and the dielectric layer, portions of the firstinsulating material are removed, and the second insulating material ismade of a silicon nitride and the first insulating material is made ofsilicon oxide.